Tree trauma

January 21, 2010

The amount of snowfall this winter has raised the question of where to put it all, and sometimes that means piling it on top of trees and other plants, but could that damage the vegetation?

"Many of the tree species native to this area are not actually harmed by the snow - they are more harmed by ice and exposure to freezing, dessicating winds," said Linda S. Jones, Ph.D., assistant professor of environmental sciences at Southwest Minnesota State University.

"When the tree trunk is surrounded by deep snow, the snow itself is not generally a problem," said Pamela Sanders, associate professor of biology at SMSU.

"The snow acts as insulation and can be important in helping some plants survive the extreme cold. Many more plants would be damaged by a cold snap without snow cover than with snow."

There's more danger of the snow physically damaging the plants, Sanders said.

"If the snow has bent the branches down, they may spring back up when the snow is gone," she said. "Sometimes the weight of the snow does break the branches, though. It's generally recommended to avoid shaking the bent branches to get the snow off; that's more likely to break them."

"Too much snowfall or ice can damage trees," said Carol Vermeersch, Master Gardener of Lyon County, but the danger is more likely to come from a less natural source.

"The trees can't take a lot of trauma. They shouldn't be pushed by snowplows or snowmoving equipment," she said.

"The biggest amount of damage is that the machines will push into the branches, mechanical damage," said Vermeersch. "They can actually push the snowbank into the tree."

If you're concerned about the safety of your trees, consider wrapping them, said Sanders and Vermeersch.

"Deep snow can lead to more damage from rabbits and other animals chewing on the tree bark," Sanders said.

"It should be wrapped if critter damage is a problem," said Vermeersch. "Mostly for younger trees; a larger tree will bounce back for the most part."

"It is a good idea to protect the trunks of thin-barked young trees to prevent both animal damage and sunscald," Sanders said. "Young trees are often damaged by the rapid temperature change resulting when the sun heats up the trunk and then a cloud hides the sun, lowering the temperature of the trunk. Many materials are sold to wrap or protect the tree trunks for the winter."

Most trees go into a hibernating state during the winter and are more active as spring approaches, but don't worry about the piled snow short-circuiting the tree's natural processes, said Vermeersch. "The thaw is ahead of the growing."